Novel superconducting articles, and methods for forming and using same

ABSTRACT

A superconducting tape is disclosed, including a substrate, a buffer layer overlying the substrate, a superconductor layer overlying the buffer layer, and an electroplated stabilizer layer overlying the superconductor layer. Also disclosed are components incorporating superconducting tapes, methods for manufacturing same, and methods for using same.

CROSS-REFERENCE TO RELATED APPLICATION(S) BACKGROUND

[0001] 1. Field of the Invention

[0002] The present invention is generally directed to superconducting orsuperconductor components, and in particular, a novel superconductingtape, power components incorporating same, and methods for utilizing andmanufacturing same.

[0003] 2. Description of the Related Art

[0004] Superconductor materials have long been known and understood bythe technical community. Low-temperature (low-T_(c)) superconductorsexhibiting superconductive properties at temperatures requiring use ofliquid helium (4.2K), have been known since about 1911. However, it wasnot until somewhat recently that oxide-based high-temperature(high-T_(c)) superconductors have been discovered. Around 1986, a firsthigh-temperature superconductor (HTS), having superconductive propertiesat a temperature above that of liquid nitrogen (77K) was discovered,namely YBa₂Cu₃O_(7−x) (YBCO), followed by development of additionalmaterials over the past 15 years including Bi₂Sr₂Ca₂Cu₃O_(10+y) (BSCCO),and others. The development of high-T_(c) superconductors has broughtpotential, economically feasible development of superconductorcomponents incorporating such materials, due partly to the cost ofoperating such superconductors with liquid nitrogen, rather than thecomparatively more expensive cryogenic infrastructure based on liquidhelium.

[0005] Of the myriad of potential applications, the industry has soughtto develop use of such materials in the power industry, includingapplications for power generation, transmission, distribution, andstorage. In this regard, it is estimated that the native resistance ofcopper-based commercial power components is responsible for quitesignificant losses in electricity, and accordingly, the power industrystands to gain significant efficiencies based upon utilization ofhigh-temperature superconductors in power components such astransmission and distribution power cables, generators, transformers,and fault current interrupters. In addition, other benefits ofhigh-temperature superconductors in the power industry include anincrease in one to two orders of magnitude of power-handling capacity,significant reduction in the size (i.e., footprint) of electric powerequipment, reduced environmental impact, greater safety, and increasedcapacity over conventional technology. While such potential benefits ofhigh-temperature superconductors remain quite compelling, numeroustechnical challenges continue to exist in the production andcommercialization of high-temperature superconductors on a large scale.

[0006] Among the many challenges associated with the commercializationof high-temperature superconductors, many exist around the fabricationof a superconducting tape that can be utilized for formation of variouspower components. A first generation of HTS tapes includes use of theabove-mentioned BSCCO high-temperature superconductor. This material isgenerally provided in the form of discrete filaments, which are embeddedin a matrix of noble metal, typically silver. Although such conductorsmay be made in extended lengths needed for implementation into the powerindustry (such as on the order of kilometers), due to materials andmanufacturing costs, such tapes do not represent a commercially feasibleproduct.

[0007] Accordingly, a great deal of interest has been generated in theso-called second-generation HTS tapes that have superior commercialviability. These tapes typically rely on a layered structure, generallyincluding a flexible substrate that provides mechanical support, atleast one buffer layer overlying the substrate, the buffer layeroptionally containing multiple films, an HTS layer overlying the bufferfilm, and an electrical stabilizer layer overlying the superconductorlayer, typically formed of at least a noble metal. However, to date,numerous engineering and manufacturing challenges remain prior to fullcommercialization of such second generation-tapes.

[0008] Accordingly, in view of the foregoing, various needs continue toexist in the art of superconductors, and in particular, provision ofcommercially viable superconducting tapes, methods for forming same, andpower components utilizing such superconducting tapes.

SUMMARY

[0009] According to a first aspect of the present invention, asuperconducting article is provided, which includes a substrate, abuffer layer overlying the substrate, a superconductor layer overlyingthe buffer layer, and an electroplated stabilizer layer overlying thesuperconductor layer. According to a particular feature, the stabilizerlayer may be formed principally of non-noble metals, such as copper,aluminum, and alloys and mixtures thereof. A noble metal cap layer maybe provided between the stabilizer layer and the superconductor layer.The electroplated stabilizer layer may overlie one of the two oppositemajor surfaces of the substrate, both major surfaces, or may completelyencapsulate the substrate, buffer layer, and superconductor layer. Thearticle may be in the form of a relatively high aspect ratio tape.

[0010] According to another aspect of the present invention, a methodfor forming a superconducting tape is provided, which includes providinga substrate, depositing a buffer layer overlying the substrate, anddepositing a superconductor layer overlying the buffer layer. Further,an electroplating step is carried out to deposit a stabilizer layeroverlying the superconductor layer.

[0011] According to another aspect of the present invention, a powercable is provided including a plurality of superconductive tapes, thesuperconductive tapes being provided in accordance with the first aspectof the present invention described above.

[0012] According to yet another aspect of the present invention, a powertransformer is provided including primary and secondary windings, atleast one of the windings including a wound coil of superconductive tapeprovided in accordance with the first aspect of the present invention.

[0013] According to yet another aspect of the present invention, a powergenerator is provided including a shaft coupled to a rotor that containselectromagnets comprising rotor coils, and a stator comprising aconductive winding surrounding the rotor. The rotor coils and/or theconductive winding include a superconductive tape generally inaccordance with the first aspect of the present invention describedabove.

[0014] According to yet another aspect of the present invention a powergrid is provided, which includes multiple components for generation,transmission and distribution of electrical power. Namely, the powergrid includes a power generation station including a power generator, atransmission substation including a plurality of power transformers forreceiving power from the power generation station and stepping-upvoltage for transmission, and a plurality of power transmission cablesfor transmitting power from the transmission substation. Distribution ofthe power is provided by utilization of a power substation for receivingpower from the power transmission cables, the power substationcontaining a plurality of power transformers for stepping-down voltagefor distribution, and a plurality of power distribution cables fordistributing power to end users. According to a particular feature ofthis aspect of the present invention, at least one of the power gridelements described above includes a plurality of superconductive tapes,provided in accordance with the first aspect of the present inventiondescribed above.

[0015] Still further, another aspect of the present invention provides amethod for laying power cable, sometimes also referred to generically as“pulling” cable. The method calls for providing a coil of power cable,and unwinding the coil while inserting the power cable into a conduit,wherein the conduit is an underground utility conduit. The structure ofthe power cable is described above, namely, includes a plurality ofsuperconductive tapes in accordance with the first aspect of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention may be better understood, and its numerousobjects, features, and advantages made apparent to those skilled in theart by referencing the accompanying drawings.

[0017]FIG. 1 illustrates an HTS conductive tape according to anembodiment of the present invention.

[0018]FIG. 2 illustrates a cross-section of a HTS tape according toanother embodiment of the present invention in which the entiresuperconductive tape is encapsulated by electroplated stabilizer.

[0019]FIG. 3 a cross-section of a dual-sided HTS conductive tapeaccording to another embodiment of the present invention.

[0020]FIG. 4 illustrates an electroplating process according to anembodiment of the present invention.

[0021]FIG. 5 illustrates the results of a current overloading test.

[0022]FIG. 6 illustrates the results of testing conducted to evaluatethe effect of overloading on the critical current of the HTS tape.

[0023]FIGS. 7 and 8 illustrate power cables incorporatingsuperconductive tapes.

[0024]FIG. 9 illustrates a power-transformer according to an aspect ofthe present invention.

[0025]FIG. 10 illustrates a power generator according to an aspect ofthe present invention

[0026]FIG. 11 illustrates a power grid according to another aspect ofthe present invention.

[0027] The use of the same reference symbols in different drawingsindicates similar or identical items.

DETAILED DESCRIPTION

[0028] Turning to FIG. 1, the general layered structure of an HTSconductor according to an embodiment of the present invention isdepicted. The HTS conductor includes a substrate 10, a buffer layer 12 aoverlying the substrate 10, an HTS layer 14 a, followed by a cappinglayer 16 a, typically a noble metal layer, and a stabilizer layer 18 a,typically a non-noble metal.

[0029] The substrate 10 is generally metal-based, and typically, analloy of at least two metallic elements. Particularly suitable substratematerials include nickel-based metal alloys such as the known Inconel®group of alloys. The Inconel® alloys tend to have desirable thermal,chemical and mechanical properties, including coefficient of expansion,thermal conductivity, Curie temperature, tensile strength, yieldstrength, and elongation. These metals are generally commerciallyavailable in the form of spooled tapes, particularly suitable for HTStape fabrication, which typically will utilize reel-to-reel tapehandling.

[0030] The substrate 10 is typically in a tape-like configuration,having a high aspect ratio. For example, the width of the tape isgenerally on the order of about 0.4-10 cm, and the length of the tape istypically at least about 100 m, most typically greater than about 500 m.Indeed, embodiments of the present invention provide for superconductingtapes that include substrate 10 having a length on the order of 1 km orabove. Accordingly, the substrate may have an aspect ratio which isfairly high, on the order of not less than 10³, or even not less than10⁴. Certain embodiments are longer, having an aspect ratio of 10⁵ andhigher. As used herein, the term ‘aspect ratio’ is used to denote theratio of the length of the substrate or tape to the next longestdimension, the width of the substrate or tape.

[0031] In one embodiment, the substrate is treated so as to havedesirable surface properties for subsequent deposition of theconstituent layers of the HTS tape. For example, the surface may belightly polished to a desired flatness and surface roughness.Additionally, the substrate may be treated to be biaxially textured asis understood in the art, such as by the known RABiTS (roll assistedbiaxially textured substrate) technique.

[0032] Turning to the buffer layer 12 a, the buffer layer may be asingle layer, or more commonly, be made up of several films. Mosttypically, the buffer layer includes a biaxially textured film, having acrystalline texture that is generally aligned along crystal axes bothin-plane and out-of-plane of the film. Such biaxial texturing may beaccomplished by IBAD. As is understood in the art, IBAD is acronym thatstands for ion beam assisted deposition, a technique that may beadvantageously utilized to form a suitably textured buffer layer forsubsequent formation of an HTS layer having desirable crystallographicorientation for superior superconducting properties. Magnesium oxide isa typical material of choice for the IBAD film, and may be on the orderor 50 to 500 Angstroms, such as 50 to 200 Angstroms. Generally, the IBADfilm has a rock-salt like crystal structure, as defined and described inU.S. Pat. No. 6,190,752, incorporated herein by reference.

[0033] The buffer layer may include additional films, such as a barrierfilm provided to directly contact and be placed in between an IBAD filmand the substrate. In this regard, the barrier film may advantageouslybe formed of an oxide, such as yttria, and functions to isolate thesubstrate from the IBAD film. A barrier film may also be formed ofnon-oxides such as silicon nitride and silicon carbide. Suitabletechniques for deposition of a barrier film include chemical vapordeposition and physical vapor deposition including sputtering. Typicalthicknesses of the barrier film may be within a range of about 100-200angstroms. Still further, the buffer layer may also include anepitaxially grown film, formed over the IBAD film. In this context, theepitaxially grown film is effective to increase the thickness of theIBAD film, and may desirably be made principally of the same materialutilized for the IBAD layer such as MgO.

[0034] In embodiments utilizing an MgO-based IBAD film and/or epitaxialfilm, a lattice mismatch between the MgO material and the material ofthe superconductor layer exists. Accordingly, the buffer layer mayfurther include another buffer film, this one in particular implementedto reduce a mismatch in lattice constants between the HTS layer and theunderlying IBAD film and/or epitaxial film. This buffer film may beformed of materials such as YSZ (yttria-stabilized zirconia) strontiumruthenate, lanthanum manganate, and generally, perovskite-structuredceramic materials. The buffer film may be deposited by various physicalvapor deposition techniques.

[0035] While the foregoing has principally focused on implementation ofa biaxially textured film in the buffer stack (layer) by a texturingprocess such as IBAD, alternatively, the substrate surface itself may bebiaxially textured. In this case, the buffer layer is generallyepitaxially grown on the textured substrate so as to preserve biaxialtexturing in the buffer layer. One process for forming a biaxiallytextured substrate is the process known in the art as RABiTS (rollassisted biaxially textured substrates), generally understood in theart.

[0036] The high-temperature superconductor (HTS) layer 14 a is typicallychosen from any of the high-temperature superconducting materials thatexhibit superconducting properties above the temperature of liquidnitrogen, 77K. Such materials may include, for example, YBa₂Cu₃O_(7−x),Bi₂Sr₂Ca₂Cu₃O_(10+y), Ti₂Ba₂Ca₂Cu₃O_(10+y), and HgBa₂Ca₂Cu₃O_(8+y). Oneclass of materials includes REBa₂Cu₃O_(7−x), wherein RE is a rare earthelement. Of the foregoing, YBa₂Cu₃O_(7−x), also generally referred to asYBCO, may be advantageously utilized. The HTS layer 14 a may be formedby any one of various techniques, including thick and thin film formingtechniques. Preferably, a thin film physical vapor deposition techniquesuch as pulsed laser deposition (PLD) can be used for a high depositionrates, or a chemical vapor deposition technique can be used for lowercost and larger surface area treatment. Typically, the HTS layer has athickness on the order of about 1 to about 30 microns, most typicallyabout 2 to about 20 microns, such as about 2 to about 10 microns, inorder to get desirable amperage ratings associated with the HTS layer 14a.

[0037] The capping layer 16 a and the stabilizer layer 18 a aregenerally implemented for electrical stabilization, to aid in preventionof HTS burnout in practical use. More particularly, layers 16 a and 18 aaid in continued flow of electrical charges along the HTS conductor incases where cooling fails or the critical current density is exceeded,and the HTS layer moves from the superconducting state and becomesresistive. Typically, a noble metal is utilized for capping layer 16 ato prevent unwanted interaction between the stabilizer layer(s) and theHTS layer 14 a. Typical noble metals include gold, silver, platinum, andpalladium. Silver is typically used due to its cost and generalaccessibility. The capping layer 16 a is typically made to be thickenough to prevent unwanted diffusion of the components from thestabilizer layer 18 a into the HTS layer 14 a, but is made to begenerally thin for cost reasons (raw material and processing costs).Typical thicknesses of the capping layer 16 a range within about 0.1 toabout 10.0 microns, such as 0.5 to about 5.0 microns. Various techniquesmay be used for deposition of the capping layer 16 a, including physicalvapor deposition, such as DC magnetron sputtering.

[0038] According to a particular feature of an embodiment of the presentinvention, a stabilizer layer 18 a is incorporated, to overlie thesuperconductor layer 14 a, and in particular, overlie and directlycontact the capping layer 16 a in the particular embodiment shown inFIG. 1. The stabilizer layer 18 a functions as a protection/shunt layerto enhance stability against harsh environmental conditions andsuperconductivity quench. The layer is generally dense and thermally andelectrically conductive, and functions to bypass electrical current incase of failure in the superconducting layer. Conventionally, suchlayers have been formed by laminating a pre-formed copper strip onto thesuperconducting tape, by using an intermediary bonding material such asa solder or flux. Other techniques have focused on physical vapordeposition, typically, sputtering. However, such application techniquesare costly, and not particularly economically feasible for large-scaleproduction operations. According to a particular feature of theembodiment, the stabilizer layer 18 is formed by electroplating.According to this technique, electroplating can be used to quicklybuild-up a thick layer of material on the superconducting tape, and itis a relatively low cost process that can effectively produce denselayers of thermally and electrically conductive metals. According to onefeature, the stabilizer layer is deposited without the use of orreliance upon and without the use of an intermediate bonding layer, suchas a solder layer (including fluxes) that have a melting point less thanabout 300° C.

[0039] Electroplating (also known as electrodeposition) is generallyperformed by immersing the superconductive tape in a solution containingions of the metal to be deposited. The surface of the tape is connectedto an external power supply and current is passed through the surfaceinto the solution, causing a reaction of metal ions (M^(z−)) withelectrons (e⁻) to form a metal (M).

M ^(z−) +ze ⁻ =M

[0040] The capping layer 16 a functions as a seed layer for depositionof copper thereon. In the particular case of electroplating ofstabilizer metals, the superconductive tape is generally immersed in asolution containing cupric ions, such as in a copper sulfate solution.Electrical contact is made to the capping layer 16 a and current ispassed such that the reaction Cu²⁺+2e⁻→Cu occurs at the surface of thecapping layer 16 a. The capping layer 16 a functions as the cathode inthe solution, such that the metal ions are reduced to Cu metal atoms anddeposited on the tape. On the other hand, a copper-containing anode isplaced in the solution, at which an oxidation reaction occurs such thatcopper ions go into solution for reduction and deposition at thecathode.

[0041] In the absence of any secondary reactions, the current deliveredto the conductive surface during electroplating is directly proportionalto the quantity of metal deposited (Faraday's Law of Electrolysis).Using this relationship, the mass, and hence thickness of the depositedmaterial forming stabilizer layer 18 a can be readily controlled.

[0042] While the foregoing generally references copper, it is noted thatother metals, including aluminum, silver, gold, and other thermally andelectrically conductive metals may also be utilized. However, it isgenerally desirable to utilize a non-noble metal to reduce overallmaterials cost for forming the superconductive tape.

[0043] While the foregoing description and FIG. 1 describeelectroplating to form a stabilizer layer 18 a along one side of thesuperconductive tape, it is also noted that the opposite, major side ofthe superconductive tape may also be coated, and indeed, the entirety ofthe structure can be coated so as to be encapsulated. In this regard,attention is drawn to FIG. 2.

[0044]FIG. 2 is a cross-sectional diagram illustrating anotherembodiment of the present invention, in which the entire superconductivetape is encapsulated with first stabilizer layer 18 a, second stabilizerlayer 18 b disposed on an opposite major surface of the superconductivetape, the first and second stabilizer layers 18 a, 18 b, joiningtogether along the side surfaces of the superconductive tape, forminggenerally convex side portions or side bridges 20 a and 20 b. Thisparticular structure is desirable to further improve current flow andfurther protect the HTS layer 14 a, in the case of cryogenic failure,superconductivity quench, etc. By essentially doubling thecross-sectional area of the deposited stabilizer layer by forming firstand second stabilizer layers 18 a and 18 b, a marked improvement incurrent-carrying capability is provided. Electrical continuity betweenstabilizer layers 18 a and 18 b may be provided by the lateral bridgingportions 20 a and 20 b. In this regard, the lateral bridging portions 20a and 20 b may desirably have a positive radius of curvature so as toform generally convex surfaces, which may further reduce build up ofelectrical charge at high voltages that HTS electric power devices willexperience. Additionally, to the extent that a suitably electricallyconductive material is utilized for the substrate 10, furthercurrent-carrying capability can be provided by encapsulation asillustrated in FIG.2. That is, the bridging portions extending laterallyand defining side surfaces of the tape may provide electrical connectionto the substrate itself, which can add to the current carryingcapability of the coated conductor (tape).

[0045] While not shown in FIG. 2, it may be generally desirable todeposit a noble metal layer along the entirety of the superconductivetape, particularly along the side surfaces of the superconductive tape,to isolate the superconductor layer 14 a from the material of thebridging portions 20 a and 20 b, which may be a non-noble metal such ascopper or aluminum as described above.

[0046]FIG. 3 illustrates yet another embodiment of the presentinvention. The embodiment is somewhat similar to that shown in FIG. 2,but essentially forms a double-sided structure, including first andsecond buffer layers 12 a and 12 b, respectively overlying first andsecond surfaces 11 a and 11 b of the substrate 10. Further, first andsecond superconductor layers 14 a and 14 b are provided, along withfirst and second capping layers 16 a and 16 b. This particular structureprovides an advantage of further current-carrying capability byutilizing both sides of the substrate for coating of the superconductorlayers 14 a and 14 b.

[0047]FIG. 4 schematically illustrates an electroplating processaccording to an embodiment of the present invention. Typically,electroplating is carried out in a reel-to-reel process by feeding asuperconductive tape through an electroplating solution 27 by feedingthe tape from feed reel 32 and taking up the tape at take-up reel 34.The tape is fed through a plurality of rollers 26. The rollers may benegatively charged so as to impart a negative charge along the cappinglayer(s) and/or the substrate for electrodeposition of the metal ionsprovided in solution. The embodiment shown in FIG. 4 shows two anodes 28and 30 for double-sided deposition, although a single anode 28 may bedisposed for single-sided electroplating. As discussed above, theelectroplating solution 27 generally contains metal ions of the desiredspecies for electrodeposition. In the particular case of copper, thesolution may be a copper sulfate solution containing copper sulfate andsulfuric acid, for example. The anodes 28, 30 provide the desiredfeedstock metal for electrodeposition, and may be simply formed ofhigh-purity copper plates. It is noted that while the rollers 26 may beelectrically biased so as to bias the superconductive tape, biasing maytake place outside of the solution bath, to curtail unwanted depositionof metal on the rollers themselves.

[0048] A particular example was created utilizing the electroplatingtechnique described above. In particular, samples were subjected to DCmagnetron sputtering of silver to form 3 micron-thick capping layers.Those samples were placed in a copper-sulfate solution and biased suchthat the capping layers formed a cathode, the anode being a copperplate. Electroplating was carried out to form a copper layer having anominal thickness of about 40 microns. Testing of the samples isdescribed hereinbelow.

[0049] Namely, a sample that is 1 cm wide, 4 cm long and with 1.7 micronthick YBCO HTS layer having a critical current I_(c) of about 111 A wassubjected to a current load of 326 A,. The sample was overloaded andvoltage data was gathered as illustrated in FIG. 5. The voltage recordedwas 44.4 mV at 326 A, which corresponds to heat dissipation of 3.6W/cm—lower than the critical heat flux density in LN₂ cooling condition5-20 W/cm². This means that this coated conductor with 50 micronstabilizer may carry a current higher than 326 A in LN₂ withoutexperiencing burning out. Without the stabilizer, the estimated powerdissipation is higher than 62.5 KW/cm² at 326 A. The foregoing indicatesthat the electroplated stabilizer layer acted as a robust shunt layer toprotect the superconducting film from burning out during the overloadingevent.

[0050] Subsequently, the sample was then subjected to a second load,following the overloading event. As illustrated in FIG. 6, the curvesshow the same I_(c) of about 111 A before and after overloading. Theforegoing indicates that the HTS tape retained its critical current evenafter the overloading.

[0051] In order to provide adequate current-carrying capability in thestabilizer layer, typically the stabilizer layer has a thickness withina range of about 1 to about 1,000 microns, most typically within a rangeof about 10 to about 400 microns, such as about 10 to about 200 microns.Particular embodiments had a nominal thickness at about 40 microns andabout 50 microns.

[0052] Moving away from the particular structure of the superconductingtape, FIGS. 7 and 8 illustrate implementation of a superconducting tapein a commercial power component, namely a power cable. FIG. 7illustrates several power cables 42 extending through an undergroundconduit 40, which may be a plastic or steel conduit. FIG. 7 alsoillustrates the ground 41 for clarity. As is shown, several power cablesmay be run through the conduit 40.

[0053] Turning to FIG. 8, a particular structure of a power cable isillustrated. In order to provide cooling to maintain the superconductivepower cable in a superconducting state, liquid nitrogen is fed throughthe power cable through LN2 duct 44. One or a plurality of HTS tapes 46is/are provided so as to cover the duct 44. The tapes may be placed ontothe duct 44 in a helical manner, spiraling the tape about the duct 44.Further components include a copper shield 48, a dielectric tape 50 fordielectric separation of the components, a second HTS tape 52, a coppershield 54 having a plurality of centering wires 56, a second, larger LN2duct 58, thermal insulation 60, provided to aid in maintaining acryogenic state, a corrugated steel pipe 62 for structural support,including skid wires 64, and an outer enclosure 66.

[0054]FIG. 9 illustrates schematically a power transformer having acentral core 76 around which a primary winding 72 and a secondarywinding 74 are provided. It is noted that FIG. 9 is schematic in nature,and the actual geometric configuration of the transformer may vary as iswell understood in the art. However, the transformer includes the basicprimary and secondary windings. In this regard, in the embodiment shownin FIG. 9, the primary winding has a higher number of coils than thesecondary winding 74, representing a step-down transformer that reducesvoltage of an incoming power signal. In reverse, provision of a fewernumber of coils in the primary winding relative to the secondary windingprovides a voltage step-up. In this regard, typically step-uptransformers are utilized in power transmission substations to increasevoltage to high voltages to reduce power losses over long distances,while step-down transformers are integrated into distributionsubstations for later stage distribution of power to end users. At leastone of and preferably both the primary and secondary windings comprisesuperconductive tapes in accordance with the foregoing description

[0055] Turning to FIG. 10, the basic structure of a generator isprovided. The generator includes a turbine 82 connected to a shaft 84for rotatably driving a rotor 86. Rotor 86 includes high-intensityelectromagnets, which are formed of rotor coils that form the desiredelectromagnetic field for power generation. The turbine 82, and hencethe shaft 84 and the rotor 86 are rotated by action of a flowing fluidsuch as water in the case of a hydroelectric power generator, or steamin the case of nuclear, diesel, or coal-burning power generators. Thegeneration of the electromagnetic field generates power in the stator88, which comprises at least one conductive winding. According to aparticular feature of the embodiment, at least one of the rotor coilsand the stator winding comprises a superconductive tape in accordancewith embodiments described above. Typically, at least the rotor coilsinclude a superconductive tape, which is effective to reduce hysteresislosses.

[0056] Turning to FIG. 11, a basic schematic of a power grid isprovided. Fundamentally, the power grid 110 includes a power plant 90typically housing a plurality of power generators. The power plant 90 iselectrically connected and typically co-located with a transmissionsubstation 94. The transmission substation contains generally a bank ofstep-up power transformers, which are utilized to step-up voltage of thegenerated power. Typically, power is generated at a voltage level on theorder of thousands of volts, and the transmission substation functionsto step-up voltages are on the order of 100,000 to 1,000,000 volts inorder to reduce line losses. Typical transmission distances are on theorder of 50 to 1,000 miles, and power is carried along those distancesby power transmission cables 96. The power transmission cables 96 arerouted to a plurality of power substations 98 (only one shown in FIG.10). The power substations contain generally a bank of step-down powertransformers, to reduce the transmission level voltage from therelatively high values to distribution voltages, typically less thanabout 10,000 volts. A plurality of further power substations may also belocated in a grid-like fashion, provided in localized areas forlocalized power distribution to end users. However, for simplicity, onlya single power substation is shown, noting that downstream powersubstations may be provided in series. The distribution level power isthen transmitted along power distribution cables 100 to end users 102,which include commercial end users as well as residential end users. Itis also noted that individual transformers may be locally provided forindividual or groups of end users. According to a particular feature atleast one of the generators provided in the power plant 90, thetransformers and the transmission substation, the power transmissioncable, the transformers provided in the power substation, and the powerdistribution cables contain superconductive tapes in accordance with thepresent description.

[0057] While particular aspects of the present invention have beendescribed herein with particularity, it is well understood that those ofordinary skill in the art may make modifications hereto yet still bewithin the scope of the present claims.

1. A superconducting article, comprising: a substrate; a buffer layeroverlying the substrate; a superconductor layer overlying the bufferlayer; and an electroplated stabilizer layer overlying thesuperconductor layer.
 2. The superconducting article of claim 1, whereinthe electroplated stabilizer layer comprises a non-noble metal.
 3. Thesuperconducting article of claim 2, wherein the non-noble metalcomprises a material from the group consisting of copper, aluminum, andalloys thereof.
 4. The superconducting article of claim 3, wherein thenon-noble metal comprises copper.
 5. The superconducting article ofclaim 1, wherein the electroplated stabilizer layer consists essentiallyof a non-noble metal.
 6. The superconducting article of claim 1, whereinthe buffer layer comprises a biaxially crystal textured film havinggenerally aligned crystals both in-plane and out-of-plane of the film.7. The superconducting article of claim 1, wherein the buffer layercomprises a barrier film.
 8. The superconducting article of claim 1,further comprising a noble metal layer provided between theelectroplated stabilizer layer and the superconductor layer.
 9. Thesuperconducting article of claim 8, wherein the noble metal layercomprises silver.
 10. The superconducting article of claim 1, whereinthe superconductor layer comprises a high temperature superconductormaterial, having a critical temperature T_(c) not less than about 77° K.11. The superconducting article of claim 1, wherein the superconductormaterial comprises REBa₂Cu₃O_(7−x), wherein RE is a rare earth element.12. The superconducting article of claim 11, wherein the superconductormaterial comprises YBa₂Cu₃O₇.
 13. The superconducting article of claim1, wherein the electroplated stabilizer layer has a thickness within arange of about 1 to 1000 microns.
 14. The superconducting article ofclaim 1, wherein the electroplated stabilizer layer has a thicknesswithin a range of about 10 to 200 microns.
 15. The superconductingarticle of claim 1, wherein the article is in the form of asuperconducting tape.
 16. The superconducting article of claim 15,wherein the substrate has an aspect ratio of not less than 10³.
 17. Thesuperconducting article of claim 15, wherein the substrate has an aspectratio of not less than 10⁴.
 18. The superconducting article of claim 15,wherein the substrate includes first and second opposite surfaces, andthe electroplated stabilizer layer includes first and secondelectroplated stabilizer layers respectively overlying the first andsecond opposite surfaces of the substrate.
 19. The superconductingarticle of claim 18, wherein the first and second electroplatedstabilizer layers extend so as to define first and second side surfacesof the superconducting tape and encapsulate the superconducting tape.20. The superconducting article of claim 19, wherein the first andsecond electroplated stabilizer layers form a convex contour along atleast a portion of the side surfaces of the superconducting article. 21.The superconducting article of claim 15, wherein the superconductingarticle has a dual-sided structure, the substrate having first andsecond surfaces that are opposite each other, the buffer layer includesfirst and second buffer layers that respectively overlie the first andsecond surfaces of the substrate, the superconductor layer includesfirst and second superconductor layers overlying the first and secondbuffer layers respectively, and the electroplated stabilizer layerincludes first and second electroplated stabilizer layers respectivelyoverlying the first and second superconductor layers.
 22. Thesuperconducting article of claim 1, wherein the electroplated stabilizerlayer is adhered without incorporation of a bonding layer.
 23. Thesuperconducting article of claim 1, wherein the electroplated stabilizerlayer is adhered without incorporation of a solder layer.
 24. Thesuperconducting article of claim 1, wherein the article is a powercable, the power cable including a plurality of superconductive tapes,each tape comprising said substrate, said buffer layer, saidsuperconductor layer, and said electroplated stabilizer layer.
 25. Thesuperconducting article of claim 24, further comprising a conduit forpassage of coolant fluid.
 26. The superconducting article of claim 25,wherein the superconductive tapes are wrapped around the conduit. 27.The superconducting article of claim 24, wherein the power cablecomprises a power transmission cable.
 28. (withdrawn) Thesuperconducting article of claim 24, wherein the power cable comprises apower distribution cable.
 29. The superconducting article of claim 1,wherein the article is a power transformer, the power transformercomprising a primary winding and a secondary winding, wherein at leastone of the primary winding and secondary winding comprises a wound coilof superconductive tape, the superconductive tape comprising saidsubstrate, said buffer layer, said superconductor layer, and saidelectroplated stabilizer layer.
 30. The superconducting article of claim29, wherein the secondary winding has a fewer number of windings thanthe primary winding, for reducing voltage.
 31. The superconductingarticle of claim 29, wherein the primary winding has a fewer number ofwindings than the secondary winding, for increasing voltage.
 32. Thesuperconducting article of claim 1, wherein the article is a powergenerator, comprising a shaft coupled to a rotor comprisingelectromagnets containing rotor coils, and a stator comprising aconductive winding surrounding the rotor, wherein at least one of thewinding and the rotor coils comprises a superconductive tape comprisingsaid substrate, said buffer layer, said superconductor layer, and saidelectroplated stabilizer layer.
 33. The superconducting article of claim1, wherein the article is a power grid, the power grid comprising: apower generation station comprising a power generator; a transmissionsubstation comprising a plurality of power transformers for receivingpower from the power generation station and stepping-up voltage fortransmission; a plurality of power transmission cables for transmittingpower from the transmission substation; a power substation for receivingpower from the power transmission cables, the power substationcomprising a plurality of power transformers for stepping-down voltagefor distribution; and a plurality of power distribution cables fordistributing power to end users, wherein at least one of the powerdistribution cables, power transmission cables, transformers of thepower substation, transformers of the transmission substation, and thepower generator comprises a plurality of superconductive tapes, eachsuperconductive tape comprising said substrate, said buffer layer, saidsuperconductor layer, and said electroplated stabilizer layer.
 34. Amethod for forming a superconducting tape, comprising: providing asubstrate; depositing a buffer layer overlying the substrate; depositinga superconductor layer overlying the buffer layer; and electroplating astabilizer layer overlying the superconductor layer, the stabilizerlayer being electrically conductive and functioning as an electricalshunt to bypass current.
 35. The method of claim 34, whereinelectroplating is carried out by passing the superconducting tapethrough an electroplating solution, wherein the tape is biased to form acathode, an anode is provided in the solution.
 36. The method of claim35, wherein the stabilizer layer comprises a non-noble metal.
 37. Themethod of claim 36, wherein the non-noble metal comprises copper. 38.The method of claim 37, wherein the solution comprises copper sulfate.39. The method of claim 35, wherein the superconducting tape is passedthrough the solution by a reel-to-reel process.
 40. The method of claim34, wherein electroplating is carried out such that the stabilizer layeroverlies one side of the substrate.
 41. The method of claim 34, whereinelectroplating is carried out such that the stabilizer layer overliesfirst and second opposite sides of the substrate.
 42. The method ofclaim 34, wherein electroplating is carried out such that the stabilizerlayer encapsulates the substrate, buffer layer, and the superconductorlayer.
 43. A method of laying power cable, comprising: providing a coilof power cable, the power cable comprising a plurality ofsuperconductive tapes, each tape comprising a substrate, a buffer layeroverlying the substrate, a superconductor layer overlying the bufferlayer, and an electroplated stabilizer layer overlying thesuperconductor layer; and unwinding the coil while inserting the powercable into a conduit, wherein the conduit is an underground utilityconduit.